The present invention relates to the image rendering arts. It finds particular application in conjunction with thermal ink jet printheads, and will be described with particular reference thereto. However, it is to be appreciated that the present invention is also amenable to other like applications.
Typically, the manufacturing of thermal ink jet printheads involves numerous complicated steps both inside and outside of a clean room. Among the process steps are a plurality of precise adhesive placements and position alignments are performed in the clean room. More specifically, constituent components of the printhead assembly have adhesives applied, are aligned and pressed together, and the adhesives cured in a heater. Typically, each separate component is bonded and cured in a separate step.
More specifically to the prior art, U.S. Pat. No. 6,229,114 to Andrews, et al. describes the construction of a thermal ink jet printhead, and is herein incorporated by reference. First, in the clean room, a die bond epoxy is applied to the bottom side of a die module 1. The die module 1 is then precisely aligned and assembled to a substrate 2, in the case of Andrews, a heat sink. Next, the die bond is cured in an oven for approximately 45 minutes or longer. After the die bond is set, wire bonds 3 are applied between a printed wiring board 4 on said substrate 2 and an electrical contact portion of the die module 1. An adhesion promoter is applied to the top surface of die module 1. A tack fluid seal 5 is precisely located and applied to one surface of the ink manifold assembly 6. The die module 1 and substrate 2 assembly and the manifold 6 an fluid seal 5 assembly are then precisely located to each other and are merged together and a UV adhesive is applied and cured The tack fluid seal is cured in an oven for approximately 45 minutes or longer. An encapsulation adhesive is then injected into the assembly to protect the wire bonds 3 from oxidation. A faceplate 7 is adhered to the operative surface of the printhead.
Once assembled, the printhead is subjected to an additional final cure, along with a series of integrity tests.
U.S. Pat. No. 4,601,777 to Hawkins, et al. describes an alternate method for constructing a thermal ink jet printhead, and is herein incorporated by reference. With reference to FIGS. 2 through 5 of the present application, aspects of existing manufacturing processes are illustrated. In FIG. 2, a daughter board 10 carries a thermal ink jet printhead 12. A portion of daughter board electrodes 14 are carried entirely on the facing side of the daughter board 10, and another portion of the electrodes 14 are carried partially on the reverse side of the daughter board 10, switching sides at inversion points 15. As seen in FIG. 3, daughter board electrodes 14 are connected to individual printhead electrodes 16. The printhead electrodes 16 are carried upon a substrate 18, as best seen in FIGS. 4 and 5. Wire bonds 20 are used to connect between each daughter board electrode 14 and its corresponding printhead electrode 16 counterpart. The wire bonds are installed with a standard wire bonding process as is known in the art.
Each printhead electrode 16 is connected to a heating element 22 (FIG. 5). A plurality of heating elements 22 are situated side by side along a front edge 24 of the substrate 18. An etched manifold 26 is precision aligned with the substrate 18 such that etched grooves 28 in the manifold 26 align precisely with the heating elements 22, defining ink jet channels between the manifold 26 and the substrate 18. Internal pathways and capillaries within the manifold allow ink from a supply aperture 30 to flow into each of the ink jet channels.
The present invention is suited for applications wherein a heat sink substrate is not needed and thermal control of the printhead is accomplished through other means known in the art. The present invention contemplates a new and improved method and apparatus that replaces the wire bonds, and condenses other bonding steps with a single step or process, overcoming the above referenced problems, and others.
In accordance with one aspect of the present invention, a method of assembling an ink jet printhead is provided. A printed wiring board is attached to an ink jet manifold. A die module is simultaneously attached to the manifold and the printed wiring board. Adhesives used to bond the die module to the printed wiring board and the manifold are simultaneously cured.
In accordance with another aspect of the present invention, a method of constructing an ink jet cartridge is provided. A fluid seal is dispensed on a first portion of a die module. An isotropic conductive adhesive is dispensed on a second portion of the die module containing a series of bumped electrical contacts. A single component is aligned with the die module, the component including a first, ink jet manifold section and a second, printed wiring board section. The die module and single component are moved into engagement, whereby a fluid seal connection is made, and an electrical connection is made in a single processing step.
In accordance with another aspect of the present invention, a thermal ink jet cartridge is provided. The cartridge includes a manifold and a printed substrate attached to the manifold. A die module single component that includes the manifold and the substrate is attached to at least a printed daughter board, the die module being at least partially attached with a flip chip bumping process.
One advantage of the present invention resides in simplified construction of an ink jet printhead.
Another advantage of the present invention resides in a more robust electrical bond.
Another advantage resides in reduced manufacturing costs.
Still further advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.